A conversation being dropped entirely would be bad, but your numbered steps say that's not happening. What you're seeing is a delay in delivery, which is normal behavior.

Since the pager does not keep a persistent connection to the hub, messages that are sent are not delivered instantly. Instead, they are delivered when that user next connects or when the hub, about once a minute, contacts the other user with an update. The hub can only make this kind of connection if the other user is not behind a firewall or router blocking it, or they have configured the firewall/router to allow incoming messages from the hub. If that is not the case, their pager will still try to contact the hub at regular intervals (a few minutes) at which time the hub will send its updates that way. If you are seeing transmission delays longer than a minute, it is a sign that one or both parties do not have their pagers, firewalls, and/or routers configured correctly.